The invention relates to a stent in the form of a substantially tubular body, including: multiple serpentine, annularly expandable elements, wherein the serpentine elements have first and second ends facing in axial direction of the stent, wherein the first and second ends have arcs; and Y-shaped connectors connecting axially adjacent ones of the serpentine elements, each of the connectors having a base arm and two fork arms, the base arm being connected to one of the arcs of the second end of one of the adjacent serpentine elements, the two fork arms being connected to two neighboring ones of the arcs of the first end of the other one of the adjacent serpentine elements in one to one correspondence, wherein in a non-expanded state of the stent the connectors extend in circumferential direction of the stent and have a curvature in the circumferential direction, the curvature in an expanded state of the stent having a size in the circumferential direction so that the connectors protrude radially outwardly over a circumference of the serpentine elements.
A stent is a medical implant that is introduced into a hollow organ to hold it open. It is a radially expandable endoprothesis, which is radially enlarged at the target position. Stents can be made of self-expanding materials or can be expanded by radial forces exerted from inside, for example by way of a balloon dilatation. Stents are made of different materials. In most cases they are made of metals such as stainless steel or from memory alloys such as Nitinol.
In the case of stents made of metal, the state of the art includes a design in which the generally tubular body of the stent has multiple serpentine, annularly expandable elements. These serpentine elements have arcs, which point in the axial direction of the stent. The arcs are connected via legs, which point in axial direction. Hereby, serpentine, annularly expandable elements that succeed each other in axial direction are interconnected via so-called connectors, which are usually arranged at the ends of the neighboring elements. Such an arrangement is known from WO 2006/022949 A1. The connectors are configured so as to enable expansion of the serpentine, ring-shaped elements. At the same time the stent is intended to have a smallest possible radius during the transluminal implantation. In WO 2006/022949 it is therefore proposed that the connectors overlap each other in the compressed position.
DE 29 825 178 U1 provides for helical connectors with multiple arms, which lead to the arcs of the neighboring elements. The helical connectors are quasi uncoiled when the stent expands so that the serpentine, annularly expandable elements, which serve the support function of the stent, can expand in radial direction.
GB 2 494 820 A1 discloses a stent for bridging an aneurysm. In the middle region, the stent is to be slightly widenable in order to introduce occlusion material into the neighboring aneurysm. Between serpentine elements, the stent has connectors, which extend in circumferential direction of the stent and have a curvature in circumferential direction of the stent. In an expanded stent, the curvature in circumferential direction is of a size so that the connectors protrude radially outwardly over the circumference of the serpentine element. While the serpentine elements substantially define a cylindrical region, an outwardly oriented bulge results in the middle section in the region of the connectors between the individual connectors. Here, the distance between the connectors is greater than in the region of the serpentine elements, so as to enable introducing occlusion material through this region into the neighboring aneurysm. A narrowing of the distances between the struts would impede the introduction of occlusion material into the aneurysm.
The state-of-the-art also includes WO 03/061528 A1, which relates to a so-called multilayer stent. There are serpentine segments and connectors. The connectors can be strongly bent and protrude outwardly over the cylindrical region of the stent.
DE 200 23 387 U1 discloses a stent with serpentine elements and connectors arranged therebetween. The connectors are configured as straight webs.
However, the connectors can also be curved, as disclosed in US 2007/0208416 A1. The connectors can allow a change of length of the stent.
The connectors known from WO 2012/071542 A2 can, in some exemplary embodiments, be configured Y-shaped. A base arm is connected with an arc at the end of a first serpentine element. The fork arms are Y-shaped, however, they divide once more so as to be respectively connected with three neighboring arcs at the end of the other serpentine, annularly expandable elements.
EP 1 703 859 B1 discloses a stent for placement on a curved region of a body cavity. The stent has serpentine elements and connectors arranged therebetween, which can be straight or curved. The connectors are not fork-shaped or Y-shaped. In contrast thereto DE 198 22 157 A1 proposes a radially expandable stent for implantation in a body vessel, in which branching connectors are provided, which however are additionally twisted in themselves. This is intended to create additional expansion possibilities in order to pass a second non-widened stent through the radial openings or even to radially widen the second stent in the region of the openings. Hereby the cross-sectional surface of the openings in the sheath surface of the stent has to be significantly enlarged. The stent is for example intended for placement in the region of branching points of vessels.